(1) Field of the Invention
The present invention relates to a thermal transfer recording apparatus for carrying out recording by fusing or sublimating ink of an ink film by means of a thermal head. More particularly, the invention relates to an improvement for preventing creases formed on the ink film in transportation after use in recording from adversely affecting a recorded material.
(2) Description of Related Art
In a known thermal transfer recording apparatus, as shown in FIG. 1, recording paper 32 is transported with rotation of a platen roller 31, and an ink film 35 is fed from a supply reel 33 to the recording paper 32 and is wound up by a takeup reel 34. A thermal head 36 is operable to transfer ink of the ink film 35 onto the recording paper 32 to effect recording. The apparatus further comprises cylindrical guide rollers 37 and 38 upstream and downstream of a transfer section defined by the platen roller 31 and thermal head 36, respectively. The upstream guide roller 37 causes the ink film 35 to advance along the recording paper 32, and the downstream roller 38 separates the ink film 35 from the recording paper 32.
Such a thermal transfer recording apparatus, generally, effects recording by fusing or sublimating the ink of the ink film for transfer to the recording paper. The sublimation type is capable of controlling an amount of color to be transferred onto the recording paper. This feature provides the advantage of recording halftone images with refinement.
However, the thermal transfer recording apparatus of the sublimation type requires a large amount of energy to be applied to the thermal head for sublimating the ink. To effect recording with the same amount of energy, a thinner plastic base film is needed for the sublimation type apparatus than for the fusion type apparatus. When heated by the thermal head for effecting recording, a thin plastic base film develops a plurality of thermal deformations. Consequently, the ink film after being used for recording has many corrugations as shown in FIG. 5.
In the known apparatus, these corrugations are pressed by the cylindrical guide roller 38 which has a smooth planar surface. As a result, the slack corrugations fold upon themselves to form bulky creases as shown in FIG. 2. These creases are formed over a range extending at its rear end to the transfer section as shown in FIG. 3, which impairs tight contact among the ink film 35, thermal head 36 and recording paper 32 thereby lowering the quality of recorded images.